Server Optimization - Site down

[محروم.كوم]

<div>Constantly needing to restart Apache because site crashes. Blank pages (or dialog to save the .php file) served up occasionally too when hitting php pages on forum or rest of site. Thanks ahead!

1) Dedicated server

2)
cpu speed/type single or dual cpus): dual
how much memory installed: 7.5 GB of memory, 4 EC2 Compute Units (2 virtual cores with 2 EC2 Compute Units each), 850 GB of instance storage, 64-bit platform
Linux distributor: Fedora release 8 (Werewolf)
apache/IIS version: Apache v2.2.8
PHP version: 5.2.4
MySQL version: 5.0.45 Source distribution

3) vBulletin version 3.8.1

4) Innodb tables - yes

5) mysql compiled/installed - ?

6) top stats - load occasionally spikes up above 5. This is tops stats after a recent restart of Apache

Code:
top - 14:26:32 up 45 days, 19:34, 1 user, load average: 1.38, 1.01, 0.71
Tasks: 88 total, 2 running, 86 sleeping, 0 stopped, 0 zombie
Cpu0 : 35.3%us, 9.3%sy, 0.0%ni, 49.7%id, 4.7%wa, 0.0%hi, 0.0%si, 1.0%st
Cpu1 : 0.0%us, 0.0%sy, 0.0%ni, 98.9%id, 0.0%wa, 0.0%hi, 0.0%si, 1.1%st
Mem: 7872040k total, 7116520k used, 755520k free, 304300k buffers
Swap: 0k total, 0k used, 0k free, 6051608k cached

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1124 mysql 15 0 648m 188m 6176 S 11 2.4 20085:42 mysqld
3838 apache 16 0 257m 15m 9432 S 8 0.2 0:00.72 httpd
3833 apache 15 0 258m 18m 11m S 7 0.2 0:00.74 httpd
3804 apache 15 0 259m 20m 12m S 5 0.3 0:02.33 httpd
3793 apache 15 0 258m 19m 12m S 2 0.3 0:02.04 httpd
3697 apache 15 0 259m 20m 12m S 2 0.3 0:06.26 httpd
3837 apache 15 0 257m 16m 10m S 2 0.2 0:00.41 httpd
3797 apache 15 0 257m 18m 12m S 1 0.2 0:01.77 httpd
3836 apache 15 0 258m 17m 10m S 1 0.2 0:00.46 httpd
3846 apache 15 0 257m 11m 6240 S 1 0.2 0:00.05 httpd
3568 apache 15 0 268m 40m 25m S 1 0.5 0:10.21 httpd
3584 apache 15 0 262m 32m 20m S 1 0.4 0:11.42 httpd
3792 apache 15 0 259m 27m 19m S 1 0.4 0:01.27 httpd
3800 apache 15 0 259m 20m 11m S 1 0.3 0:01.59 httpd
3825 apache 15 0 259m 19m 11m S 1 0.3 0:00.95 httpd
3831 apache 15 0 258m 18m 11m S 1 0.2 0:01.34 httpd
7) cat /etc/my.cnf
Code:
[mysqld]
#datadir=/var/lib/mysql
datadir=/mnt/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
# Default to using old password format for compatibility with mysql 3.x
# clients (those using the mysqlclient10 compatibility package).
old_passwords=1
max_connections=700
max_allowed_packet=16M
key_buffer=64M
myisam_sort_buffer_size = 64M
join_buffer_size = 1M
read_buffer_size = 1M
sort_buffer_size = 1M
table_cache = 256
thread_cache = 8
thread_concurrency = 2
myisam_data_pointer_size = 7
ft_min_word_len = 3

[mysqld_safe]
#log-error=/var/log/mysqld.log
log-error=/mnt/logs/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
8) mysql variables
<div style="margin:20px; margin-top:5px"> Code:

auto_increment_increment 1
auto_increment_offset 1
automatic_sp_privileges ON
back_log 50
basedir /usr/
bdb_cache_size 8388600
bdb_home /mnt/mysql/
bdb_log_buffer_size 131072
bdb_logdir
bdb_max_lock 10000
bdb_shared_data OFF
bdb_tmpdir /tmp/
binlog_cache_size 32768
bulk_insert_buffer_size 8388608
character_set_client latin1
character_set_connection latin1
character_set_database latin1
character_set_filesystem binary
character_set_results latin1
character_set_server latin1
character_set_system utf8
character_sets_dir /usr/share/mysql/charsets/
collation_connection latin1_swedish_ci
collation_database latin1_swedish_ci

collation_server latin1_swedish_ci
completion_type 0
concurrent_insert 1
connect_timeout 5
datadir /mnt/mysql/
date_format %Y-%m-%d
datetime_format %Y-%m-%d %H:%i:%s
default_week_format 0
delay_key_write ON
delayed_insert_limit 100
delayed_insert_timeout 300
delayed_queue_size 1000
div_precision_increment 4
engine_condition_pushdown OFF
expire_logs_days 0
flush OFF
flush_time 0
ft_boolean_syntax + -> __DEFINE_LIKE_SHARE__